1. Field of the Invention
The present invention relates to heddle frames which are mounted on weaving looms and which are connected to a dobby or other mechanism for forming the shed, in order to produce a fabric in accordance with the desired weave.
2. History of the Related Art
As is known, heddle frames are constituted by the assembly of four separate elements, namely two superposed horizontal crosspieces and two lateral uprights. The edge of the crosspieces faces the inside and are fitted with a rail for fixing the hooks provided at the ends of the yarn-guide heddles. In order to facilitate positioning of these heddles, the upright-crosspiece assembly arranged in each of the corners of the frame is in easily dismountable form. The present invention is precisely based on the observation that the choice of the mode of assembly is more delicate than it might appear at first sight.
Certain constructions have adopted a system of assembly allowing a perfect rigidity of the frame to be obtained, but such a system often employs a relatively high number of separate pieces and fixing members, thus rendering the dismounting and reassembly manoeuvres fastidious. On the contrary, other solutions proposed have rendered operation easy, but this advantage is generally acquired to the detriment of solidity.
European Pat. No. 0189216 describes a system of dismountable assembly in which each upright comprises a nose element projecting laterally on the wall of the upright facing the inside of the frame and of which the horizontal edges form bearing surfaces adapted to cooperate with a fixed piece and a spring leaf. These two pieces are connected to each other by a locking screw in order to act as jaws for immobilizing the above-mentioned nose element.
It will be noted that, although such an arrangement ensures simplicity of manoeuvre due to the uniqueness of the screw for closing the jaws, it has the drawback of applying to the uprights of the frame bending moments due to the lateral offset of the projecting nose element with respect to the vertical axis of the uprights.